This should really be built into Alfred. When you're browsing the filesystem, you should be able to navigate to the directory where you want to create the file/folder and start typing the name of the new file/folder as if you were trying to navigate to it. Instead of that big useless blank space below, it could show "Create new file at <path + what you've typed so far>" as an option. To create a folder, just put a slash at the end and it'll change to say "Create new folder at <path + what you've typed>". Or you could have both options appear below at the same time to avoid having to type the slash. It could also be smart to new nested folders, so you could /just/keeping/typing/your/path and it would create all the necessary new folders.
